Ethylene has two carbon atoms bonded to each other with a double bond. Two hydrogen atoms are bonded to each carbon. When polymerizing, the double bond is broken, and new sigma bond between two carbons of two ethylene molecules takes place. In other words, polyethylene is produced by an addition reaction of the monomer ethylene. Its repeating unit is —CH2-CH2-. Thus, this has a very simple structure with long chain carbon atoms. Polyethylene is used for pipes that carry petroleum products, such as gasoline and diesel.
Joining polyethylene pipes to fiberglass sumps is difficult. Over time, any joint between fiberglass and polyethylene tends to leak. Since the purpose of the sump is to prevent leaking, a better solution is needed to prevent leaking where polyethylene piping passes through the wall of a fiberglass sump.